The present invention relates to a touch-panel device for detecting a touched position of a finger of an operator, conductive pen or the like to a surface of a touch-panel which has an arrangement that a conductive membrane is provided on a surface of a substrate. More particularly, the present invention relates to a touch-panel device which is used for a tablet for selecting and for touching by a user for responding questions, or which is used for selecting information item (menu) by a user which is displayed on a surface of a display {CRT(Cathode Ray Tube), liquid crystal panel or the like } connected to a computer information processing system, especially.
Such touch-panel device is proposed in Patent Application Publication No. Shou 56-500230 gazette entitled xe2x80x9cTouch-panel system and methodxe2x80x9d, Japanese Patent Laid-Open Publication No. Shou 63-108423 gazette entitled xe2x80x9cFinger touching type coordinates outputting apparatusxe2x80x9d, Japanese Patent Publication No. hei 6-12508 gazette entitled xe2x80x9ccontact type position detection apparatusxe2x80x9d and the like.
FIG. 11 is a schematic diagram useful in understanding touching position detection principal of those devices.
To both ends of a conductive membrane 1 on a touch-panel, one end of current measurement resistors 2, 3 are connected, respectively. The other end of the current measurement resistors 2, 3 have a common connection point. The common connection point is connected to an AC power source 4 one end of which is connected to the ground. The conductive membrane 1 is touched at its arbitrary point using a finger, or an impedance Z such as a conductive pen or the like one side of which is connected to the ground.
Under this condition, it is supposed that the resistance value of the conductive membrane 1 between one end and the finger is RL, that the resistance value of the conductive membrane 1 between the other end and the finger is RH, and that the entire resistance of the conductive membrane 1 is R0. Further, the resistance of the current measurement resistors 2, 3 are determined to be the resistance value RK, and the voltages of the both ends of the current measurement resistors 2, 3 are determined to be V1 and V2, respectively.
When such assumptions are made, the following equation is satisfied.                                           R            L                                R            0                          =                                                            R                K                            ⁡                              (                                                      V                    2                                    -                                      V                    1                                                  )                                                                    R                0                            ⁡                              (                                                      V                    1                                    +                                      V                    2                                                  )                                              +                                    V              2                                                      V                1                            +                              V                2                                                                        (        I        )            
From this equation (1), a touching point of a finger can be detected based only upon the measurement values of voltages V1 and V2.
Japanese Patent Publication No. Hei 6-12508 entitled xe2x80x9cContact type position detection apparatusxe2x80x9d discloses an arrangement that electrodes are provided at outer peripheral sections of the conductive membrane of position detection region, the electrodes having smaller resistance value with respect to the conductive membrane.
The xe2x80x9cTouch-panel system and methodxe2x80x9d and the xe2x80x9cFinger touching type coordinates output apparatusxe2x80x9d have following disadvantages.
a. In the equation (1), the resistance value of the resistance of the conductive membrane should be substituted. But, when a constant value is input, detection accuracy is lowered depending upon the change following passage in time of the conductive membrane and the installment environment of the conductive membrane. Further, when the resistance value is measured at every position detection and when the resistance value is substituted, measurement circuitry becomes complicated and expensive. Furthermore, changing in resistance value of the conductive membranes is great therefore yield of mass produced conductive membranes is lowered. As a result, a touch-panel is increased in cost.
b. Electrodes made of low resistance conductive material have resistance value which are provided outer peripheral section of the conductive membrane. Therefore, the value which is RL/R0 at both ends in X-axis or Y-axis becomes 0 or 1 at corner sections and becomes a value different from 0 or 1 at sections which are not the corner sections, as is illustrated in FIG. 9. As a result, detection accuracy is greatly lowered when the equation (1) is employed.
The xe2x80x9cContact type position detection apparatusxe2x80x9d has following disadvantage.
Improvement in values for sections apart from both edges in X-axis or Y-axis is insufficient, the values being different from 0 or 1, as is illustrated in FIG. X2.
The present invention was made in view of the above problems.
It is an object of the present invention to offer a touch-panel device which has high position detection accuracy, and which can be manufactured with a low cost.
It is another object of the present invention to offer a touch-panel device which has high position detection accuracy, and which has short operating and processing time, and which can be manufactured with a low cost.
A touch-panel device of claim 1 according to the present invention is a touch-panel device which comprises a touch-panel including a substrate and a conductive membrane provided on the substrate, an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane, and current measurement sections for measuring a first current supplied through the first point and a second current supplied through the second point, and wherein a touched position is calculated based upon the measured first current and the measured second current, and
The touch-panel device is characterized in that the device comprises an impedance which is connected by interposing a switch between one end of the AC current generation section and a connection point of the first point and one end of the current measurement section, at least, and wherein
A touch position on the touch-panel is calculated based upon a current measurement value measured by the current measurement means when the switch is turned ON and another current measurement value measured by the current measurement means when the switch is turned OFF.
When this touch-panel device is employed, a touch position on the touch-panel is calculated based upon a current measurement value measured by the current measurement means when the switch is turned ON and another current measurement value measured by the current measurement means when the switch is turned OFF. Therefore, variation in resistance value of the conductive membrane or changing in resistance value of the conductive membrane following passage of time are not needed to be taken into consideration which is described later, so that touch-position detection with high accuracy is realized.
A touch-panel device of claim 2 according to the present invention is characterized in that the switch is turned ON and turned OFF at every constant interval, a current measurement value measured by the current measurement means when the switch is turned ON is memorized, and a touch position on the touch-panel is calculated based upon the memorized current measurement value and a current measurement value measured by the current measurement means when the switch is turned OFF.
When this touch-panel device is employed, changing in resistance of the conductive membrane following passage of time is applied correction calculation and is renewed and memorized at every constant interval, therefore touch-position detection with high accuracy is realized. Further, it is not necessary that the switch is turned ON and turned OFF and self-correction calculation is applied at every touch position detection, therefore a measurement time is shortened.
A touch-panel device of claim 3 according to the present invention is a touch-panel device which comprises a touch-panel including a substrate and a conductive membrane provided on the substrate, an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane, and current measurement sections for measuring a first current supplied through the first point and a second current supplied through the second point, and wherein a touched position is calculated based upon the measured first current and the measured second current, and
The touch-panel device is characterized in that a chart is provided which includes corrected touch position information each corresponding to a calculation value of the touch position, and wherein
The corrected touch position corresponding to the calculation value of the touch position is obtained from the chart.
When this touch-panel device is employed, the chart is provided which includes corrected touch positions each corresponding to each calculation value of touch position in at least one direction, and shifting in touch position due to resistance of the conductive membrane is corrected. Therefore, touch position detection with high accuracy is realized.
A touch-panel device of claim 4 according to the present invention is a touch-panel device which comprises a touch-panel including a substrate and a conductive membrane provided on the substrate, an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane, and current measurement sections for measuring a first current supplied through the first point and a second current supplied through the second point, and wherein a touched position is calculated based upon the measured first current and the measured second current, and
The touch-panel device is characterized in that a correction operation formula for correcting the calculated touch position is memorized, and wherein
The calculated touch position is applied to the correction operation formula so as to perform the correction operation of the touch position on the touch-panel.
When this touch-panel device is employed, shifting in touch position due to the resistance of the conductive membrane is corrected, so that touch position detection with high accuracy is realized.
A touch-panel device of claim 5 according to the present invention is characterized in that electrodes made of low resistance conductive material are provided at outer peripheral sections of the conductive membrane of the touch-panel.
When this touch-panel device is employed, shifting in touch position due to resistance of the conductive membrane is reduced by providing the electrodes made of low resistance conductive material are provided at outer peripheral sections of the conductive membrane of the touch-panel.
A touch-panel device of claim 6 according to the present invention is a touch-panel device which comprises a touch-panel including a substrate and a conductive membrane provided on the substrate and electrodes made of low resistance conductive material lower than the resistance of the conductive membrane which electrodes are provided at peripheral sections of the conductive membrane, an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane, and current measurement sections for measuring a first current supplied through the first point and a second current supplied through the second point, and wherein a touched position is calculated based upon the measured first current and the measured second current, and
The touch-panel device is characterized in that the resistance value of the electrodes is determined to be an optimum value using calculation formulae of:
CA=(X*RA)/(8*xcfx81)and
CB=(Y*RB)/(8*xcfx81).
Wherein, CA [mm] is a maximum curvature of linearity in periphery of electrode section in X-axis direction, CB [mm] is a maximum curvature of linearity in periphery of electrode section in Y-axis direction, RA [xcexa9] is a sum of resistances between electrodes of 1 electrodes in X-axis direction, RB [xcexa9] is a sum of resistances between electrodes of 1 electrodes in Y-axis direction, X [mm] is a length of the electrode in X-axis direction, Y [mm] is a length of the electrode in Y-axis direction, and xcfx81[xcexa9/xe2x96xa1] is a resistance value of the conductive membrane on the surface of the substrate.
When this touch-panel device is employed, the resistances RA, RB of the electrode patterns are obtained using calculation formulae, then the values of the maximum curvatures CA, CB are calculated. And, the resistances RA, RB are obtained by trial and error which make the values of the maximum curvatures CA, CB to be the minimum values, then the panel electrodes in this condition are determined to have optimum values in resistance value. Shifting in touch position due to resistance of the conductive membrane is reduced by the above determination.
A touch-panel device of claim 7 according to the present invention is a touch-panel device which comprises a touch-panel including a substrate and a conductive membrane provided on the substrate and electrodes made of low resistance conductive material lower than the resistance of the conductive membrane which electrodes are provided at peripheral sections of the conductive membrane, an AC current generation section for supplying AC currents to the conductive membrane through a first point and a second point which are at outer peripheral sections of the conductive membrane, and current measurement sections for measuring a first current supplied through the first point and a second current supplied through the second point, and wherein a touched position is calculated based upon the measured first current and the measured second current, and
The touch-panel device is characterized in that the resistance values of the electrodes are sequentially changed from the first point or the second point of the electrodes to the central section of the electrode.
When this touch-panel device is employed, the resistance values of the electrodes are sequentially changed from the first point or the second point of the electrodes to the central section of the electrode by changing the thickness or the width of the electrodes, for example. Therefore, shifting in touch position due to the resistance of the conductive membrane is reduced.
A touch-panel device of claim 8 according to the present invention is characterized in that the resistance values of the electrodes are sequentially changed from the first point or the second point of the electrodes to the central section of the electrode by changing the thickness of the electrodes.
When this touch-panel device is employed, shifting in touch position due to the resistance of the conductive membrane is reduced. Further, the width of the electrodes can be determined to be small so that the touch-panel device is decreased in size and is decreased in cost.
A touch-panel device of claim 9 according to the present invention is characterized in that the resistance values of the electrodes are sequentially changed from the first point or the second point of the electrodes to the central section of the electrode by changing the width of the electrodes.
When this touch-panel device is employed, shifting in touch position due to the resistance of the conductive membrane is reduced.
A touch-panel device of claim 10 according to the present invention is characterized in that the resistance values of the electrodes are sequentially changed from the first point or the second point of the electrodes to the central section of the electrode by constructing the electrodes by connecting a plurality of electrode element.
When this touch-panel device is employed, shifting in touch position due to the resistance of the conductive membrane is reduced.